Local hemodynamic properties which exist at branchpoints of major arteries are of interest because of their reported role in the development of atherosclerosis. Clearly, branchpoints can have an early susceptibility towards atherosclerosis. Relatively little is known of the detailed behavior of blood flow at branchpoints in comparison to straight arterial sections. Dogs and swine are animal models commonly used for cardiovascular studies, but no data exist which allow a description of the local flow properties at branchpoints in these two animal species. Quantitative information on the local flow properties at sites known to have a susceptibility to atherosclerosis is clearly needed. A technique has been developed using a pulsed ultrasound Doppler velocity meter which permits the measurement of velocity distributions in arteries for extended periods of time using implantable polystyrene transducers. The local hemodynamic properties will be measured in swine and dogs at two locations in the abdominal aorta and in both iliac arteries. Specifically, velocity transducers will be implanted in the abdominal aorta at a site immediately distal to the left renal artery and proximal to the aortal-iliac junction. Transducers will also be placed around both iliac arteries where they originate from the aorta. Recordings of velocity distributions will be made bimonthly in the animals for up to one year. The time-varying blood velocity data recorded in small increments across the vessel will be recorded on magnetic tape. Velocity profiles, time-varying velocities, and peak and average shear stresses will be calculated and plotted. These data will be analyzed with respect to differences among locations and between species. Silastic models of the arterial vasculature in the animals will provide a basis for interpreting differences in the velocity distributions.